Optical Image Encryption using Fringe Projection Profilometry, Fourier Fringe Analysis, and RSA Algorithm

Optical image encryption is one of the most promising technologies being investigated in the field of data communication and information technology. In this paper, a novel image encryption system based on virtual optical technique, Fourier transform phase retrieval algorithm and RSA public key exchange is proposed. In this strategy, a gray-level image is captured using a digital camera and encrypted using a linear grating superposed on the reflected intensity map of the object. A speckle mask is simulated and used as a secret key in both transmission and reception ends so that the receiver can identify the authenticity of the ciphertext by using the speckle pattern in the decryption process. The decryption method is performed to recover the phase of the deformed grating pattern. Towards this, Fourier transform based phase retrieval and sequential line scan phase unwrapping algorithm is utilized. The simulation results demonstrate the validity of the encryption method and the high robustness against potential attacks. To determines the accuracy of the information retrieved by the proposed technique, root mean square error is calculated between the original image and retrieved image. The proposed technique is also applicable for the information authentication.